Cellular communications systems continue to grow in popularity and have become an integral part of both personal and business communications. Cellular telephones allow users to place and receive voice calls most anywhere they travel. Moreover, as cellular telephone technology has increased, so too has the functionality of cellular devices and the different types of devices available to uses. For example, many cellular devices now incorporate personal digital assistant (PDA) features such as calendars, address books, task lists, etc. Moreover, such multi-function devices may also allow users to wirelessly send and receive electronic mail (email) messages and access the Internet via a cellular network and/or a wireless local area network (WLAN), for example.
Accordingly, because of the widespread use and reliance on cellular devices, many users carry their cellular devices on their person much of the day. Yet, since cellular devices are frequently communicating with a cellular network even when a user is not participating in a phone call, they are frequently emitting radio frequency (RF) signals. When in close proximity to other electronic equipment, such as personal audio devices (e.g., portable radios, MP3 players, etc.), these RF signals may cause interference which results in an audible buzz or other undesirable sound from the personal audio device.
One exemplary portable audio device is disclosed in U.S. patent application publication no. 2003/0059071. This application is directed to an integrated personal audio device that provides hearing protection for a user. The device includes a flexible band configured to extend at least partially around a head of a user. An audio transmitter is coupled to the band. The band has two legs that terminate at respective end portions. Each end portion is coupled to an audio speaker, which is electrically connected to the audio transmitter. A hearing protector is mounted onto each respective audio speaker. Moreover, the audio transmitter may include RF shielding to filter radio interference associated with nearby electric equipment, for example.
While such devices may provide some reduction in unwanted RF interference, further RF interference protection may be required to significantly mitigate the effects of RF interference from a nearby cellular device, for example.